Moulding presses



1962 J. c. VAN HOUTEN 3,068,512

MOULDING PRESSES Filed Nov- 6. 1959 3 Sheets-Sheet l FIGJ VENTOR J. VAN HOUTEN AGENT Dec. ,18, 1962 Filed Nov. 6. 1959 J. C. VAN HOUTEN MOULDING PRESSES 3 Sheets-Sheet 2 INVENTOR J. C. VAN HOUTEN AG lT 2 Dec. 18, 1962 J. c. VAN HOUTEN MOULDING PRESSES 3 Sheets-Sheet 3 Filed NOV. 6, 1959 INVENTOR J. c. VAN HOUTEN 3,068,512. MGULDING PRESSES lian Chrisiofiel Van Houten, Baarn, Netherlands, assignor to North American Philips Company Inc, New York, N.Y., a corporation of Delaware Fit-ed Nov. 6, 1%9, Ser. No. 851,358 Claims priority, application Netherlands Nov. 26, 1958 5 Claims. (Cl. 185.3)

This invention relates to a press for moulding articles, such as disc-shaped phonograph records, from thermoplastic and thermosetting material.

In moulding gramophone records, it is known to use dies shaped in the form of a book comprising two plates which are hinged to one another and to which the stampers are secured. One of the plates has a centering stud while the other plate has a centering aperture cooperating with this stud. Such a die has large advantages. Since the die is readily transportable, separate hot and cold press blocks can be used, so that the press need not be changed over and this is highly advantageous from the point of view of thermal economy. in addition, the operation of the press requires less physical strength, since the heavy pressing blocks are stationary.

The present invention relates to a moulding press using book-type dies and is characterized in that the press has a lifting table comprising three adjacent positions for the dies, the central position corresponding to the location of the pressing blocks, wh le the two other positions lie each on one side of the central position, the lifting taole being capable of performing a vertical movement, which preferably is controlled electrically and produced hydraulically, by which movement the dies disposed on the lifting table can be brought to the level of the hot or cold pressing block, while furthermore means are provided which permits of horizontal transport from one position to an other. Hence, the present invention enables a single press to be operated with three dies simultaneously; one die is disposed in the cold part, a second die is disposed in the hot pressing block, while the third die is emptied and provided with new moulding material, and these operations require only a single worker who, furthermore, has to do light work only. Consequently, the press is particularly suitable for operation by unskilled labour. A further advantage of the press in accordance with the invention consists in that it can also be operated with one die or with two dies.

In one embodiment of the invention, there is provided on the lifting table a transport device in which two dies can be placed side by side and which is capable of performing a horizontal movement over the lifting table. Although in principle the dies can bear directly on the lifting table and can be arranged thereon, such a transport device facilitates the transport of the dies, while mistakes are impossible.

In order to enable the die to be introduced in an already hot condition into the hot pressing block, with a resulting shortening of the pressing period proper, according to a further embodiment of the invention means are provided to preheat a die arranged on the lifting table of the transport device in one of the free positions. Accordingto another embodiment of the invention, this preheating treatment can be effected by providing a movable electric heater element which preferably is controlled electrically and moved hydraulically and can be applied to the opened upper part of the die. Thus, the preheating treatment is effected while the die is empty and opened.

According to an embodiment of the invention, the lower part of the die is preheated by a vertically movable, preferably electrically controlled and hydraulically moved electric preheating element. In one embodiment of the invention the movements of the two preheating elements Stats atent can be effected, for example, through a lever mechanism, by the upper part being raised to open the die.

However, it is simpler, if, according to another embodiment of the invention, the raised upper part of the die bears against a switch which controls the movements of the electric heater elements both in time and in direction.

According to an embodiment of the invention, preferably the upper part of the die is held in the open position during the preheating treatment by mechanical or electromagnetical means.

After the die has been cooled and again placed on the lifting table or transport device, it can be opened manually. in one embodiment of the invention, however, preferably means are provided to open the die, at least partly, in one of its positions. According to a further embodiment of the invention, however, in this event preferably at least a portion of the upper part is made greater, in a direction parallel to the axis of the hinge, than the lower part, while the transport device is provided, for one position of the die, with guidingmembers which embrace the sides or" the lower part of the die and are open at least at the side of the press. Thus, when the die is opened, its lower part is held; a transport device is required. According to an embodiment of the invention, the operation of opening the die can be effected in that the transport device is provided with two substantially vertical partitions, which are bevelled at the side of the press and are arranged one on each side of the guiding grooves, the greatest height of these partitions being at least equal to the spacing between the inner side of the upper part of the die and the upper surface of the transport device when the die is opened to an extent such that the centering stud is disengaged from the upper Stamper, while the bevelled portion has a minimum height which at most is equal to the spacing between the upper and the lower parts of the closed die. Hence, this method of partly opening the die also requires a transport device, since the dies cannot be transported over the lifting table if this latter is provided with partitions.

A separate transport device is also necessary if, in another embodiment of the invention, studs adapted to move vertically, which preferably are controlled electrically and moved hydraulically, are provided on both sides of the guiding grooves, which studs are capable of lifting the upper part of the die through a distance such that this part is completely disengaged from the centering stud. The advantage of this embodiment consists in that the mould is not opened unless this is necessary.

For optimum tuning of the various cycles with one another to ensure the regular course of operations, according to a further embodiment of the invention, the press is designed so that the heated pressing blocks and the cooled pressing blocks, in relationship with the thermal energy delivered or withdrawn, are proportioned so that the time required to heat the pressing blocks is approximately equal to the time required to cool them.

In order that the invention may be readily carried out, embodiments thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which FIG. 1 shows diagrammatically five successive steps I-V of the operation of a press for manufacturing gramophone disc records,

FIG. 2 is a plan view of a so-called book, that is to say, a die for pressing gramophone records,

FIG. 3 is a side elevation of the book of HG. 2 viewed in the direction of the arrow,

FIG. 4 is a front elevation of the book of FIG. 2, likewise viewed in the direction of the arrow,

FIG. 5 is a plan view of the pressing table of a press in a position corresponding to the position I of FIG. 1,

FIG. 6 is a sectional view of the table shown in FIG. 5

taken on the line VIVI, viewed in the direction of the arrow,

FIG. 7 is a sectional view of the table of FIG. taken on the line VIIVII, viewed in the direction of the arrow,

FIG. 8 shows an alternative embodiment of a lifting device for the upper part of a book,

FIG. 9 shows a book with the upper part opened, and

FIG. 10 shows an alternative embodiment of the heating system for the upper part.

In FIG. 1, reference numeral 1 denotes a stationary part of a hydraulic press, which part comprises a heated portion 2, an insulating portion 3 and a cooled portion 4. A pressing block 5, which is continuously heated, for example electrically, is connected to a pressing plunger 6 capable of vertical movement. A cooled pressing block 7 is connected to a likewise hydraulically movable plunger 8. A lifting table 9 can be moved vertically by two hydraulic plungers 1t} and 11. A transport slide 12 is mounted on this lifting table 9. The press contains two dies in the form of books b and c, the book .5 being heated and the book 0 being cooled. Another book a, which is filled with the material to be moulded, for example polyvinyl chloride, lies on the slide 12. As is shown in position II, the lifting table is now moved to its uppermost position and, simultaneously or after the table has reached this position, the pressing block 5 is slightly raised. New book b can be pulled out of the press onto the slide 12. Then this slide is moved to the right and the book a is introduced into the press, which subsequently closes so that the book a is heated, as is shown in position III. Then the lifting table 9 is lowered, until the position IV is reached, while the cooling block 7 descends slightly. The book 0, of which the contents are now sufficiently cooled, can be pulled out of the press onto the slide 12; then the slide is moved to the left, so that the book b can be introduced into the press, after which the cooled block 7 is raised and the book b and its contents are cooled. Meanwhile, the book c becomes completely free, as is shown by position V, and the moulded record can be removed from this'book, after which the book is again filled with moulding material and the condition of position I is reached. Thus, the correct position relative to the press is always reached by'the complete movement of the slide 12, the operation of the press limited to moving the comparatively light books into and out of the press and to moving the slide and furthermore to the filling and emptying of the books. As will be described hereinafter, a part of these operations can be performed automatically.

Preferably, the dies are shaped in the form of a book of the kind described in copending US. application Serial 'No. 720,687 filed March 11, 1958, now Patent No. 2,984,-

867. Such a book comprises two parts 12a and 13 which are connected by means of two spring plates 14 and 15 to a hinge 16. Stamper blocks 17 and 18, on which the Stampers are mounted, are secured to the parts 12a and l3.

4 parallel to the lower part until'the centering'stud'is disengaged from the upper part, and this movement is made possible by the spring plates 14 and 15. To effect this vertical movement of the upper part, bevelled pressure members 31 are mounted on the slide, which members engage the lower surface of the widened upper part 12a of the book. The lower part 13 is held by grooves in members 32 which are secured to the slide. Hence, when the book 6 is removed frornthe press in position IV of FIG. 1, the lower part 13 slides in the grooves of the members 32 and at the same time the upper part 12a is forced vertically upwards by the pressure members 31. When this upper part is disengaged from the centering stud 19, it can be swung open normally about the hinge 16.

One of the Stampers is provided with a centering stud 19. The edges of the stampers slightly project beyond the parts 12a and 13 to ensure satisfactory engagement in the press with the heated or cooled pressing blocks. The parts 12a and 13 are provided with slots 26 to form handles by means of which the book can be transported and opened.

FIGS. 5, 6 and 7 show the position I, the lifting table and the slide being again designated 9 and 12, respectively. The lifting table 9 is raised or lowered by two plungers 21, which co-operate with two cylinders 22 and are connected to the lifting table by junction pieces 23. The slide 12is provided wtih two blocks 24 and 25 which slide in the grooves'26 and 27 of the lifting table. The slide is provided with an ear'23 to which a plunger 29 is connected which can move in a cylinder 36. Thus, the slide 12 can be moved hydraulically. It "will be appreciated that the hook cannot normally be opened due to the provision of the comparatively long-centering stud 19; the upper part must firstbe moved vertically and An alternative embodiment for opening the book is shown in FIG. 8. In this embodiment, the lifting table 9 contains a cylinder 33 in which a plunger 34 is adapted to move. This plunger 34 is connected by levers 35 and $5 to pressure studs 37 and 38 which pass through apertures in the lifting table and in the slide. If, now, the plunger 3 is hydraulically moved to the left, the pressure studs 37 and 38 engage the projecting portions of the upper part 12a, so that this part is raised vertically.

Furthermore, provision is made of a cylinder 39 in which a plunger 40 is adapted to move. This plunger carries an electric heater element 41. In the lowermost position of the lifting table, this heater element 41 can be raised through the apertures in the lifting table 9 and in the slide 12 so as to engage the lower surface of the stamper '18. This permits of heating the Stampers before it is filled with the moulding material, so that the heat treatment proper can be shorter. Obviously, in this event two pressure studs 37 and 38 are provided on either side, plungers 34 being disposed on both sides of the heater element 41 and of the plunger 29. The upper part of the book can also be preheated during filling. For this purpose, the upper part 1212, which carries the stamper 17, in its open condition engages a heater element 42. A switch 43 is pushed in so that an electromagnet d4 is energised and the upper, part 12a is held magnetically. A push-button 45 breaks the circuit, so that the die can be closed. The switch 43 also controls the movement of the element 41. Alternatively, the heater element 42 may be provided with a plunger 46, as is shown in FIG. 10. In this event, this element is slightly retracted normally and is moved to the upper part by operating the switch 43. Furthermore, the two elements need not continuously engage the upper and lower parts of the book when'this is opened; a known timing relay can be used to ensure that the elements are withdrawn after a certain period of time. Furthermore, the elements can be provided with thermostats so that the temperature is kept substantially constant. When the element 42 is adapted to move, the upper part is preferably not held magnetically but locked mechanically.

A large part of the described operations can be simply co-ordinated automatically. For this purpose, provision can be made, as is shown in FIG. 1, of limit switches 46 and 47 between which the lifting table 9 can move. Furthermore, limit switches 48 and 49 are provided, one on each side of the slide, and finally a switch 50 is mounted on said slide. The various valves which control the hydraulic systems, can be controlled electrically in known manner, if required, by means of a relay with delayed operation. Thus, the entire cycle will be as follows: when the die is filled in position I of FIG. 1, the lifting table is raised by pushing a button; when the table has reached its uppermost position, the switch 46 is operated so that the heated part of the press opens. The movement of the book b closes the switch 50 so that the slide is moved to the right until the switch 49 is operated. Now another switch is opened by inserting the book a into the press, so that the press closes and the lifting table 9 is lowered until the switch 47 is closed. The press operator now has time to take the book 0 from the press since the cooling block 7 now opens. When the book has been taken from the press, the slide moves to the left owing to the fact that the book 0 again operates a switch, until the slide strikes the switch 48. Then the book b can be inserted in the press, but at the same time the device for lifting the upper part of the book 0 is rendered operative. Hence, this upper part can be opened and now the arrangement shown in FIG. 10 becomes operative, the heater element 41 engaging the lower part and the heater element 42 the upper part. After the book has been filled and closed, the element 41 has been lowered and the element 42 has been removed, the entire cycle can again be started by pushing a button.

Obviously, the entire cycle need not be made automatic in this manner; a number of the described automatically operated switches can be displaced by manually operated push-buttons. It is desirable, however, that the time required to heat the book between the pressing blocks and 2 should be substantially equal to the time required for cooling between the pressing blocks 4 and '7.

In a press which was rendered semi-automatic in the manner described, the time required to mould a gramophone record of diameter inch was 90 seconds, that is to say, the time interval between the filling of book a and the instant at which this book, after its return to the first position, is again opened; hence, the moulding period per record is /2 minute. The work of the operator comprises only moving the books into and out of the press, filling and emptying the book and pushing a few buttons, so that this work is highly suitable for unskilled persons of limited strength.

It will be appreciated that it is not necessary to operate the press with three books. If a limited number of records is required, two books or even one book can be used. The advantages of easy operation are retained, however, obviously the press will work less economically, since thermal energy is lost and, in addition, the capacity of the press is not completely utilised.

What is claimed is:

1. A press for moulding with book-type dies articles, such as phonograph records, from thermoplastic or thermosetting material; comprising hot-pressing means adapted to receive a die including a hot-pressing member; coldpressing means adapted to receive a die and including a cold-pressing member, said two means being arranged vertically one above the other; elevating means for supporting two dies and movable vertically between one position level with said hot-pressing means and a second position level with said cold-pressing means, said elevating means having a central portion adapted to receive the dies and to be positioned adjacent either of said first two means and two end portions adapted to receive the dies and located one on each side of said central portion; and transport means for moving the dies horizontally between said three portions.

2. A press for moulding With book-type dies articles, such as phonograph records, from thermoplastic or thermosetting material; comprising hot-pressing means adapted to receive a die including a hot-pressing member, coldpressing means adapted to receive a die and including a cold-pressing member, said two means being arranged vertically one above the other, elevating means for supporting two dies and movable vertically between one position level with said hot-pressing means and a second position level with said cold-pressing means, said elevating means having a central portion adapted to receive the dies and to be positioned adjacent either of said first two means and two end portions adapted to receive the dies and located one on each side of said central portion; transport means for moving the dies horizontally between said three portions; and means associated with said elevating means to preheat the dies.

3. A press for moulding with book-type dies articles, such as phonograph records, from thermoplastic or thermosetting material; comprising hot-pressing means adapted to receive a die including a hot-pressing member, coldpressing means adapted to receive a die and including a cold-pressing member, said two means being arranged vertically one above the other, elevating means for sup-' porting two dies and movable vertically between one position level with said hot-pressing means and a second position level with said cold-pressing means, said elevating means having a central portion adapted to receive the dies and to be positioned adjacent either of said first two means and two end portions adapted to receive the dies and located one on each side of said central portion; transport means for moving the dies horizontally between said three portions; electrical means associated with said elevating means to preheat the dies; and means actuated by the opening of the dies to energize said electrical means.

4. A press for moulding with book-type dies articles, such as phonograph records, from thermoplastic or thermosetting material; comprising hot-pressing means adapted to receive a die including a hot-pressing member; coldpressing means adapted to receive a die and including a cold-pressing member, said two means being arranged vertically one above the other, elevating means for supporting two dies and movable vertically between one position level with said hot-pressing means and a second position level with said cold-pressing means, said elevating means having a central portion adapted to receive the dies and to be positioned adjacent either of said first two means and two end portions adapted to receive the dies and located one on each side of said central portion; transport means for moving the dies horizontally between said three portions; an electrical heater to preheat the dies; and means controlled by the opening of the dies to bring the dies and said heater into heat-transferring relationship.

5. A press for moulding with book-type dies articles, such as phonograph records, from thermoplastic or thermosetting material; comprising hot-pressing means adapted to receive a die including a hot-pressing member, coldpressing means adapted to receive a die and including a cold-pressing member, said two means being arranged vertically one above the other; elevating means for supporting two dies and movable vertically between one position level with said hot-pressing means and a second position level with said cold-pressing means, said elevating means having a central portion adapted to receive the dies and to be positioned adjacent either of said first two means and two end portions adapted to receive the dies and located one on each side of said central portion; transport means for moving the dies horizontally between said three portions; hydraulic means for moving said elevating means, a slide adapted to receive two dies and movable horizontally on said elevating means between said three portions; hydraulic means to move said slide between said two positions; and means to automatically open the dies upon movement of said slide.

References Cited in the file of this patent UNITED STATES PATENTS Millholf Nov. 11, 1958 

